Generally speaking modern planters turn the meter about the same speed in every crop.  The soybean meters have many times the number of holes in the corn meters.  I can't say off the top of my head how many holes are in the 1200 disks (i think Corn is 40, and beans are closer together and double or triple rowed)  but the Cyclo corn drum is available in 24 and 36 hole whereas the soybean drum comes in 140 and 280 hole. 

The motors I used are somewhere about 7 cubic inches.  I had to match what was already on the planter so I had to go elsewhere because Surplus Center did not have them.  I think that they are the Ross whcih the Dr mentioned...I can do look if you want.